懷疑 = have something uncertain/unsure in heart = doubt/suspect

[疑]由「矢arrow」「匕->比compare」「定」構成, 意思為uncertain/doubt/suspect
[定]means (no compare arrow) = sure

[疑]unsure, [定]sure

「懷疑」的用法也不能只說「我懷疑」必須在「我懷疑」的後面加上所懷疑的事，這時「懷疑」是verb。

但是如果只用「S＋懷疑」時是錯誤的，因為詞性變成SV(status verb)，這時就必須說成「我很懷疑」而不需加所懷疑的事，這時的「懷疑」和verb的「懷疑」是不同詞性的，我想你的解釋裡漏了這個部分。

我認為還是用doubt才對。

我怀疑他是坏人。
wǒ huáiyí tā shì huàirén.
I suspect he’s a bad person.

But one couldn’t normally say:

*我怀疑他是好人。
wǒ huáiyí tā shì hǎorén.
I suspect he’s a good person.

I’m thinking a better all-around translation for 怀疑 would be “have a bad feeling (that…)”.

True, I would probably say “doubt” in that sentence as well, but “suspect” would be understood, but as you say, 我怀疑 is definitely “doubt.” Hmm… this is one of those cases where I wish my grounding in English was better than it is

As for “I doubt you are a thief,” I would personally say 我觉得你不是小偷, and drop the “doubt” all together. I think that’s closer to how I would say it in English, too — “I don’t think you’re a thief.” I think 我不怀疑你是小偷 would work too.

Anyway, you’re right about most dictionaries having “doubt” and “suspect” as a definition for the word. It’s one of those things that I had never really thought about before you brought it up, and now that I am, I’m worried that I’ve been totally confusing people with it

Excellent point! But (maybe this is just my personal preference) I don’t often say “I suspect his gratitude’s sincerity.” I personally would say “I doubt his gratitude’s sincerity.”

My other example where someone just says, “wǒ huáiyí” 我怀疑 in response to something someone else said would sound very strange (and, I dare say, have no meaning) if translated “I suspect,” or “I suspect it.”

The real problem I’m addressing is that all my dictionaries give “doubt” and “suspect” as definitions definition for huáiyí 怀疑 and I was looking for a way to explain how to keep those two English definitions straight.

Also, going from English to Chinese it’s important to understand how this little word works. For example, imagine I’m translating for someone and they say:

“Ok, I know everyone thinks this guy stone my cell phone, but tell him I doubt he’s a thief.”

I can’t just say, what I would have said before:

tā huáiyí nǐ shì xiǎotōu
他怀疑你是小偷

Because that means: “I suspect you are a thief”!

How would you translate “I doubt you are a thief”?

Clarifying questions: always a good idea.

But um, my impression of yǐwéi 以为 is that it’s usually used to say “you thought (but you were wrong)…” Unless you know for sure that these numbers are NOT all the same person’s, I would suggest juéde 觉得 or rènwéi 认为 or even xiǎng 想 for your clarifying question.

I suspect she’ll be late today.
I suspect his gratitude’s sincerity.

I’ve always thought of 怀疑 is simply ‘suspect’ and have never really had problems with the two roles.

I assume you got external validation on all three translations from a native speaker?

I honestly think if I heard that statement I’d follow up by asking a clarifying question with a verb that doesn’t have the same issue:

哪，你以为都是一个人的吗？